Pre-and early postpartum maternal behavior in the New Zealand white rabbit consists of an elaborate pattern of nestbuilding behavior that results in a straw nest built in a burrow, lined with loosened fur plucked from the female's ventrum. By contrast, postpartum maternal behavior is abbreviated, consisting of a single brief daily visit to the nest (< 4 min) during which the female nurses the pups at the same time daily for about a month. Serum levels of estradiol, testosterone, progesterone, and prolactin obtained from females during pregnancy and lactation have been correlated with nestbuilding behavior, food intake, and nursing. Studies are proposed on ovariectomized females to stimulate burrowing behavior, straw carrying, hair loosening, plucking and carrying to the nest, and to determine the hormonal regulation of food intake and nursing behavior using systemic injections of these hormones and blocking prolactin release with bromocryptine. Brain implants of appropriate hormones will be used to delineate brain regions responsive to hormonal stimulation of nestbuilding and nursing. Behavioral interactions during nestbuilding will be studied by shaving females to prevent use of hair providing hair obtained by shaving the female, or preventing hair loosening by blocking enzymatic reduction of testosterone. Female dependence on pup stimulation to maintain maternal responsiveness postpartum will be studied by early separation from the pups and by stimulus restriction during the prolonged contact which occurs on the first day, and, in addition, by depriving females of pup stimulation during the first week by anesthetizing them during the daily nursing.